Myocytic hypertrophy and increased perimyocytic fibrosis accompany intraventricular pressure overload (hypertension and aortic stenosis) in human hearts. Myocardial structure as a result of arterial hypertension, but not aortic stenosis, is also characterized by intramyocardial arteriole wall-thickening and increased perivascular fibrosis. Thus, distinct structural reaction patterns are noted in the cardiac hypertrophy associated with hypertension and aortic stenosis.